Various abbreviations that appear in the specification and/or in the drawing figures are defined as follows:
ADCanalog to digital converterAPaccess pointBTSbase transceiver stationCPcyclic prefixDACdigital to analog converterDVBdigital video broadcastFDDfrequency division duplexFFTfast Fourier transformGPSglobal positioning systemGSMglobal system for mobile communicationIFFTinverse fast Fourier transformIPinternet protocolMACmedium access controlNodeBbase stationP/Sparallel/serialQAMquadrature amplitude modulationS/Pserial/parallelTDDtime division duplexTDMtime division multiplexWCDMAwideband code division multiple accessWLANwireless local area networkWMNwireless mesh network
Wireless mesh networks have been undergoing significant research and development, and interest in high performance infrastructure wireless mesh networks has increased. Different from sensor and ad-hoc networks, with very low energy consumption but low throughput and long delay, the high performance infrastructure WMN is expected to provide carrier-grade service. One important WMN application is to provide wideband data access for mobile users.
The use of a WMN for a purely data backhaul application has also gathered momentum. The WMN backhaul-only focus is on the data transport part, as it can be used to provide data backhaul for the multi-access part in accordance with various requirements, such as WLAN AP, GSM BTS, WCDMA NodeB and DVB-T BTS. By using the WMN based data backhaul network the operator can provide cost effective data backhaul for the NGM (new growth market, both GSM and WBA systems) in a rural area and/or for a micro/Pico BTS in an urban area.
The topology of the WMN-based data backhaul network basically includes a plurality of static nodes which communicate with each other over wireless links. These static nodes function in a manner analogous to wireless routers. Among the static nodes there is at least one root node which connects with the backbone network (which may be, for example, fiber, cable or microwave-based), and the data traffic flows to and from the root node. The WMN-based data backhaul network can be organized as tree structure, implying that at each moment each mesh node in the tree only has one parent node. Conversely, each node may act as parent node for one or more children nodes.
In a wireless mesh network for data backhaul transmission, the path between the root node and a given mesh node can span several hops, and each hop adds an undesirable delay to the transmission. In addition, in some mesh networks the delay of each hop is not fixed and can vary based on, for example, the time of a transmit opportunity. As a result, the total transmission delay can be unknown from transmission to transmission. It is therefore desirable to find an efficient mesh network operational mode that both minimize the multi-hop delay and that provides a known transmission delay.
Reducing the maximum number of hops is a direct method to reduce the transmission delay for a boundary mesh node. However, this approach can reduce the coverage area of the WMN.
Using a reduced frame time one method to reduce the per hop delay. However, as compared to the use of a longer frame the overall data throughput is reduced. Further, in some cases even the use of a very short frame time does not significantly improve the delay experienced by the boundary mesh node.